Apparatus have been employed in the prior art in which a liquid is directed under pressure into one or more nozzles and ejected in a stream from the discharge outlet of each nozzle directly into the inlet of a hollow tube which is spaced from the nozzle. The discharge outlet of the nozzles and the inlets of the hollow tubes are located within a suction chamber connected to a source of fluid, e.g., air, to be pumped. In the course of passage between the discharge outlet of the nozzles and the inlets of the hollow tubes, the liquid streams ejected from the nozzles create a negative pressure within the suction chamber which draws the air through the suction chamber and into the hollow tubes. The air is intermixed with the liquid stream within the hollow tubes forming a combined fluid stream which is ejected from the outlet end of the hollow tubes. An apparatus of this general type is shown, for example, in U.S. Pat. No. 3,707,067 to Dietrick.
The Dietrick apparatus and similar designs have been found to be useful in applications such a gas scrubbing wherein the air drawn into the hollow tubes contains undesirable contaminants. The contaminated air is thoroughly intermixed with the liquid streams within the hollow tubes so that contaminants are removed from the air by the liquid before the air is discharged to atmosphere. The liquid is subsequently filtered by a device such as disclosed in U.S. Pat. No. 3,618,772.
One problem With apparatus of the type described above is that their usefulness is limited in applications wherein a relatively high vacuum is required, such as in high vacuum pumps or suction generators. In order to create a high vacuum within the suction chamber of such apparatus, air must be prevented from leaking from the outlet end of the hollow tubes into the suction chamber, i.e., in an upstream direction opposite to the flow of liquid and air therethrough. Although the liquid streams ejected from the nozzles into the hollow tubes tend to expand radially outwardly therein, no effective seal is created between the liquid stream and internal wall of the hollow tubes. As a result, a leakage path is provided for air to pass from the outlet end of the hollow tubes which is at approximately atmospheric pressure and the suction chamber which is at less than atmospheric pressure.
Another problem with apparatus of the type disclosed in U.S. Pat. No. 3,707,067 is that the manufacture and assembly thereof is made difficult by the large number of parts employed in their construction. For example, each of the nozzles and hollow tubes in such apparatus is a separate element mounted by a threaded connection within or in communication with the suction chamber. In addition, a number of structural elements are required to form the suction chamber and other parts of the apparatus. All of these elements must be interconnected by screws, and seals are employed therebetween to avoid fluid leakage. The many structural elements, seals and joint connections add expense and difficulty to the manufacture and assembly of apparatus such as disclosed in U.S. Pat. No. 3,707,067.